A phosphor material (or a phosphor) is used as a wavelength converter (or a phosphor converter=pc), which absorbs a first wavelength emitted from a light source and re-emits a second wavelength longer than the first wavelength (luminescent material). Phosphors comprising silicates, phosphates (for example, apatite) and aluminates as host materials, with transition metals or rare earth metals added as activating materials to the host materials, are widely known. As blue LED light sources, in particular, have become practical in recent years, the development of white light sources utilizing such blue LEDs in combination with such phosphor materials is being energetically pursued.
Especially luminescent materials based on the so-called “SiAlON”-system have found the focus of attention in the field due to their good optical features.
However, there is still the continuing need for luminescent materials which are usable within a wide range of applications and especially allow the fabrication of phosphor warm white pcLEDs with optimized luminous efficiency and color rendering.